Three recent issues of the Water Bear web base have been devoted entirely to the discussion of the bizarre microscopic animalcule Cornechiniscus cornutus.  Some of you possibly have considered this topic a little bit too special for a microscope amateur magazine. Moreover, not everybody has a moss cushion with a Cornechinicus population in her/his drawer.

So, we will return now to a more general topic. Already before we have heard that terrestrial tardigrades can be stored in the  dry   state for years. They can be revived at any time just by adding a droplet of water. You might have a look at this phenomen once again using our   photomicrograph series   of such a water bear revival.

But, when kept in water alive the terrestrial (moss inhabiting) tardigrades turn out to be very choosy with respect to their environment. The water quality in a petri dish is continuously degrading and our water bears tend to become victims of bacteria and funghi when kept in wet condition all the time.
Of course we should try to create an agreable environment for our tardigrades in order to follow their behaviour and development continuously. A good micro aquarium is indispensible. Most of the regional laboratory equipment dealers will simply laugh at you when you will ask them about the commercial availability of such a micro aquarium for water bears.
But times have not always been that bad. When looking in the microsope literature of your grandparents you will find a broad range of solutions and moreover you will enjoy it as an aesthetical pleasure. The graphical quality of those 19th century textbooks is unequalled and after some time of study you will really admire those authors and editors who built fine illustrations on a very restricted basis of b/w line drawings only. Just have a look at the following frontispiece table:

Frontispiece table from Jabez Hogg'' textbook "The Microscope", 1st edition, 1854. On a monument's base we find a contemporary small microscope (left) by the splendid Ross Company, U.K. and an older "Screw Barrel" microscope (right) dating back to the 18th century.

In this book and in others we come across a wide range of possible technical solutions for microscope micro aquaria. We will look at them in order to find one that might be suited for our special task. Some of the devices might look a little bit crude at the first sight but we should by no means underestimate the creativity our our ancestors!

Aquarium microscope, ca. 1860.
The image and product shown here apparently was appreciated very much by the audience and therefore have been shown many times.

The above figure represents a small microscope dipping directly into the water and being protected by a glass container looking like an ordinary test tube. It can be moved all over the surface area by a positioning device working in a similar way as the mechanical stage of a microscope. As a consequence, a really big water volume can be studied and a large fraction of the volume is accessible for the microscope. The big water volume has its well-known advantages: the physico-chemical properties of the water will change only slowly and there is no danger that it might suddenly dry out like a droplet of water on our microscopy glass slides. On the other hand, after some time this ingenious machinery will certainly cause some back-ache and you will certainly know what you have done after some hours of study. Last but not least when being transferred to the water bear topic it becomes clear that the water bears will run away out of sight and will get lost somewhere within the big volume, so we will not be able to study them in a continuous manner and we will not be able to find certain individuals again a few days later.

Our ancestors therefore tried very soon to reduce the dimensions of the aquaria and by this facilitated the study with optical devices. A good example for a moderate solution is the following "portrait" orientation aquarium with attached loupe.

"Portrait" orientation aquarium for the study of water animalcules at an approximate 10x magnification.
Note the rack and pinion focusing on the left hand side and the pantograph type x-y stage.

A very practical approach came from a female Irish microscope amateur, The Honourable Mrs. Ward  (1827-1869). It might possibly be a solution for a more comfortable long time observation and doesn't need any additional investment:

"Arrangement of Microscope for viewing minute Water Animals" (after WARD)

But do not think that Mrs. Ward might have been a primitive person. As many other microscopists of her time she owned a so-called "Live-box" which she did in fact use for her water bear investigations.

Schematic diagram showing a so-called "Live-Box" (top view and cross section).







In the cross section it becomes apparent that the height of the water volume between the cover glass and the bottom glass can be adjusted by movement of the concentric brass tubes.

Fine microscope by the Ross company, ca. 1850, with additional equipment.

On the bottom left there is the "it-goes-without-saying included"  Live-Box.

BTW: a further forgotten useful equipment were the 3D forceps which allow free movement of an object under the microscope (bottom, middle).

A modern, mechanically less sophisticated variation of the Live-box is the washer-type design made out of modern materials:

Simple micro aquarium. The ring can be made out of glued plexi glass, or, even more primitive, consist of a water-proof washer. Some people use a simple thread layed down in form a ring. All those containers can be closed by means of a normal cover glass.

For higher magnifications and smaller organisms (bacteria) the principle of the hanging droplet can be used:

The small droplet hanging down from the cover glass into a glass slide with a cavity allows the observation of very small organisms in constant humidity. And, of course, there are variations, e.g. with paraffine as an addional sealing material in order to prevent desiccation.

Left: simple compressorium. The screw is used to adjust the distance between the bottom glass and the cover glass.
Bottom: more complex compressorium. The screw on the left is working against the spring R and allows a very smooth height adjustment.

In practice you will soon notice that a micro aquarium can cause problems, e.g. in servicing, when you want to change a fraction of the water. There might be deposits of unwanted materials in the edges, there might be unwanted evaporation ...

An ingenious approach and a solution for most problems is the "capillary cage" design as suggested by Mr. Varley already 1831 (!):

The construction of the capillary cage allows the water volume to be confined between a bottom glass and a cover glass without being confined mechanically by side walls. It can be perfectly sealed, opened and re-closed easily without any problems. Water can be taken out or added without major disturbances or losses.
But there is one serious problem, of course: where are you going to buy a capillary cage micro aquarium nowadays?

We will come up with a surprising suggestion and a solution to meet all the above requirements of the capillary cage design: you will find it here, in our next issue (December) which will be on-line by end of November. And you will not be asked to send 100 US $ to us. The advice will be free, the material needed will be surprisingly cheap and you will not need a degree in engineering in order to get a working micro aquarium.

We would like to add an urgent request to all amateur microscopists: please be aware of what is usual called human superiority and character and therefore do not simply use the compressoria in order to squeeze or squash the water bears.
Remember that your body mass is many million times above the one of the water bears. So don't behave like a brute giant and try to respect the integrity of the water bears even though there might be many billions everywhere around you. Just imagine a situation in which you were under the cover glass and the water bear sitting behind the microscope! It might be your next life ...

Link:  Mike Dingley's MICSCAPE article about  Compressoria

© Text, images and video clips by  Martin Mach  (webmaster@baertierchen.de).
Water Bear web base is a licensed and revised version of the German language monthly magazine  Bärtierchen-Journal . Style and grammar amendments by native speakers are warmly welcomed.

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